1) Field of the Disclosure
The disclosure relates generally to systems and methods using conductive materials printed or deposited with direct write printing processes, and more particularly, to lightning protection systems and methods using conductive materials, such as nanoparticle ink, printed or deposited with direct write printing processes. The disclosure also relates generally to methods and systems of fabricating sensors, and more particularly, to methods and systems for fabricating nanoparticle piezoelectric sensors deposited onto a structure.
2) Description of Related Art
Composite materials are used in a wide variety of structures and component parts, including in the manufacture of air vehicles, such as aircraft, spacecraft, and rotorcraft, and in the manufacture of watercraft, automobiles, trucks, and other vehicles, due to their high strength-to-weight ratios, corrosion resistance, and other favorable properties. In particular, in aircraft construction, composite structures and component parts are used in increasing quantities to form the fuselage, wings, tail section, skin panels, and other component parts of the aircraft.
However, composite materials are less conductive than metallic materials, and composite structures and component parts may have difficulty dissipating electric charge or energy from a lightning strike or from P-static (precipitation static), as quickly or efficiently as metallic structures and component parts.
Known systems and methods have been developed to manage lightning strikes and static buildup, for example, P-static, on composite structures of air vehicles, such as aircraft. Several known systems and methods add metallic conductors or incorporate metal foil systems of various configurations into composite structures and component parts. The addition of such metallic conductors may include metallic diverter strips applied to composite structures and component parts. The incorporation of such metal foil systems may include the use of copper or aluminum foil in the form of metallic mesh embedded within composite structures and component parts. However, such known metallic diverter strips and embedded metallic mesh may have difficulty handling the fatigue of a flexible surface, such as a flight control surface of a wing of an aircraft, and may affect the structure of the composite material or component part they are applied to or embedded within.
In addition, known applique-based systems may be used to manage lightning strikes and static buildup for example, P-static, on composite structures of air vehicles, such as aircraft. Such known applique-based systems use alternate layers of dielectric and conductive materials applied as an applique over the composite structure surface and secured to the surface with an adhesive. However, such known appliques may not be installed or applied during manufacturing or during layup of the part, and may typically be installed or applied after manufacturing in a secondary operation. This may result in decreased producibility. Further, such known appliques typically include a continuous layer applied with an adhesive and may be difficult to repair or replace in situ.
Another difficulty with such known systems and methods of managing lightning strikes and static buildup is that they are not direct write processed, but may require manufacturing with a special layup process, which may increase the time and expense of manufacturing, or may require application in a less permanent, secondary operation after manufacturing.
Accordingly, there is a need in the art for an improved electrical conductor pathway system and method for managing electric charge, such as from lightning strikes and P-static, on the surface of composite structures and component parts, that provide advantages over known systems and methods.
Small sensors, such as microsensors, may be used in a variety of applications including in structural health monitoring (SHM) systems and methods to continuously monitor structures, such as composite or metal structures, and to measure material characteristics and stress and strain levels in order to assess performance, possible damage, and current state of the structures. Known SHM systems and methods may include the use of small, stiff, ceramic disk sensors integrated onto a polyimide substrate and connected to power and communication wiring. Such known sensors are typically manually bonded to a structure with an adhesive. Such manual installation may increase labor and installation costs and such adhesive may degrade over time and may result in the sensor disbonding from the structure. In addition, such known sensors may be made of rigid, planar, and/or brittle materials that may limit their usage, for example, usage on a curved or non-planar substrate surface may be difficult. Moreover, in a large array of such known sensors, the amount of power and communication wiring required may increase the complexity and the weight of the structure.
In addition, known sensor systems and methods, such as micro-electromechanical systems (MEMS) and methods, may include the use of depositing onto a substrate piezoelectric sensors, such as lead zirconate titanate (PZT) sensors, having nanoparticles. Known methods for making such MEMS may include molten salt synthesis of PZT powder for direct write inks. However, the applications of the PZT sensors fabricated with such known methods may be limited by the physical geometry of the PZT sensors. Such physical geometry limitations may result in inadequate sensing capacities or inadequate actuation responses. Further, the PZT sensors fabricated with such known methods may be unable to be applied or located in areas where their function may be important due to the PZT sensor fabrication method. For example, known molten salt synthesis methods may require processing at higher temperatures than certain application substrates can tolerate.
Further, such known MEMS systems and methods may also include the use of sensors having nanoparticles which have not been crystallized and which may be less efficient than nanoparticles which have been crystallized. Non-crystallized structures typically have greater disorganization resulting in decreased response sensitivity to strain and voltage, whereas crystallized structures typically have greater internal organization resulting in increased response sensitivity to strain and decreased necessity for energy to operate. In addition, the nanoparticles of the sensors may be too large for some known deposition processes and systems, such as a jetted atomized deposition (JAD) process, and such nanoparticles may require a high temperature sintering/crystallization process which may result in damage to temperature sensitive substrates or structures.
Accordingly, there is a need in the art for an improved method and system of fabricating PZT piezoelectric sensors having nanoparticles that may be used in structural health monitoring systems and methods for structures, where such improved method and system provide advantages over known methods and systems.